let's us do the math here to see which is quicker since you have a lot of fallacies in your stance.... controls: he lives in Crystal City, he'll buy tickets for both Flying and Amtrak in advance

Flying: walks to DCA (assuming 10 mins) 25 mins before LGA flight> gets on flight and flies out (25 mins to clear pre-flight/security + actual flight time of 45 mins=70 mins)> lands and takes 10 mins to deboard plane and get on Subway to go to his exact location which takes 42 mins (Google Maps LGA to Columbus Circle) total time to reach Columbus Circle: 2 hrs 12 mins

Amtrak: from Crystal City he takes the Metro (i'm even assuming he lives right next to the Metro) to Union Station (30 mins travel time according to Google Maps) 5 mins before it leaves>departs in the non-Acela (since u cited it as being $31/one way) which averages 3 hrs 20 mins>gets off Amtrak and transition to Subway from Penn Station to Columbus Circle which is 9 mins total time to reach Columbus Circle: 4 hrs 4 mins

Conclusion: flying is 1 hr 52 mins faster than the Amtrak, even if he took the Acela that'll only subtract 30-40 mins at best off the time depending on which Acela time he chooses. Price Analysis: Flying: free to walk to DCA + $108 roundtrip flight (just checked American Airlines flights DCA2LGA) + Subway ticket $2.75= $110.75. Amtrak: Metro to Union Station ($2.75)+ two Amtrak coach tickets at $31/each way ($62 total)+$2.75 subway ticket from Penn Station= $67.5. Amtrak coach is cheaper but at a cost of almost 2 hrs one way in life time. Multiple his hourly wage by X2 to account for value of time and Flying wins hands down. Amtrak Acela would exceed the overall cost of Flying too.

Seat size doesn't matter when you're on a 40 min flight. In addition, the accrued flying miles he gains can be used for vacation. What other ridiculous assertions do you have for me?